var stop, staticx;
var img = new Image();
img.src = "imgs/snow.png";

function Sakura(x, y, s, r, fn) {
	this.x = x;
	this.y = y;
	this.s = s;
	this.r = r;
	this.fn = fn;
}

Sakura.prototype.draw = function(cxt) {
	cxt.save();
	var xc = 40 * this.s / 4;
	cxt.translate(this.x, this.y);
	cxt.rotate(this.r);
	cxt.drawImage(img, 0, 0, 40 * this.s, 40 * this.s)
	cxt.restore();
}

Sakura.prototype.update = function() {
	this.x = this.fn.x(this.x, this.y);
	this.y = this.fn.y(this.y, this.y);
	this.r = this.fn.r(this.r);
	if(this.x > window.innerWidth ||
		this.x < 0 ||
		this.y > window.innerHeight ||
		this.y < 0
	) {
		this.r = getRandom('fnr');
		if(Math.random() > 0.4) {
			this.x = getRandom('x');
			this.y = 0;
			this.s = getRandom('s');
			this.r = getRandom('r');
		} else {
			this.x = window.innerWidth;
			this.y = getRandom('y');
			this.s = getRandom('s');
			this.r = getRandom('r');
		}
	}
}

SakuraList = function() {
	this.list = [];
}
SakuraList.prototype.push = function(sakura) {
	this.list.push(sakura);
}
SakuraList.prototype.update = function() {
	for(var i = 0, len = this.list.length; i < len; i++) {
		this.list[i].update();
	}
}
SakuraList.prototype.draw = function(cxt) {
	for(var i = 0, len = this.list.length; i < len; i++) {
		this.list[i].draw(cxt);
	}
}
SakuraList.prototype.get = function(i) {
	return this.list[i];
}
SakuraList.prototype.size = function() {
	return this.list.length;
}

function getRandom(option) {
	var ret, random;
	switch(option) {
		case 'x':
			ret = Math.random() * window.innerWidth;
			break;
		case 'y':
			ret = Math.random() * window.innerHeight;
			break;
		case 's':
			ret = Math.random();
			break;
		case 'r':
			ret = Math.random() * 6;
			break;
		case 'fnx':
			random = -0.5 + Math.random() * 1;
			ret = function(x, y) {
				return x + 0.5 * random - 1.7;
			};
			break;
		case 'fny':
			random = 1.5 + Math.random() * 0.7
			ret = function(x, y) {
				return y + random;
			};
			break;
		case 'fnr':
			random = Math.random() * 0.03;
			ret = function(r) {
				return r + random;
			};
			break;
	}
	return ret;
}

function startSakura() {

	requestAnimationFrame = window.requestAnimationFrame ||
		window.mozRequestAnimationFrame ||
		window.webkitRequestAnimationFrame ||
		window.msRequestAnimationFrame ||
		window.oRequestAnimationFrame;
	var canvas = document.createElement('canvas'),
		cxt;
	staticx = true;
	canvas.height = window.innerHeight;
	canvas.width = window.innerWidth;
	canvas.setAttribute('style', 'position: fixed;z-index:1;left: 0;top: 0;pointer-events: none;');
	canvas.setAttribute('id', 'canvas_sakura');
	document.getElementsByTagName('body')[0].appendChild(canvas);
	cxt = canvas.getContext('2d');
	var sakuraList = new SakuraList();
	for(var i = 0; i < 50; i++) {
		var sakura, randomX, randomY, randomS, randomR, randomFnx, randomFny;
		randomX = getRandom('x');
		randomY = getRandom('y');
		randomR = getRandom('r');
		randomS = getRandom('s');
		randomFnx = getRandom('fnx');
		randomFny = getRandom('fny');
		randomFnR = getRandom('fnr');
		sakura = new Sakura(randomX, randomY, randomS, randomR, {
			x: randomFnx,
			y: randomFny,
			r: randomFnR
		});
		sakura.draw(cxt);
		sakuraList.push(sakura);
	}
	stop = requestAnimationFrame(function() {
		cxt.clearRect(0, 0, canvas.width, canvas.height);
		sakuraList.update();
		sakuraList.draw(cxt);
		stop = requestAnimationFrame(arguments.callee);
	})
}

window.onresize = function() {
	var canvasSnow = document.getElementById('canvas_snow');
	canvasSnow.width = window.innerWidth;
	canvasSnow.height = window.innerHeight;
}

img.onload = function() {
	startSakura();
}

function stopp() {
	if(staticx) {
		var child = document.getElementById("canvas_sakura");
		child.parentNode.removeChild(child);
		window.cancelAnimationFrame(stop);
		staticx = false;
	} else {
		startSakura();
	}
}